Yeah, okay, you can say all of that. Sure. But in the end, whether or not people like the designs is entirely a matter of personal opinion. miHoYo's only obligation is creating a character design that doesn't look ugly, and at that they succeed. I don't really hate any of Genshin's characters. Everything beyond that, though, is in the eye of the beholder.

I think I should've clarified. I like "boring" characters. I didn't like Genshin's character designs when the game released and still don't like them now. It's a major factor in why I don't play the game anymore. Some of my favorite designs are literal NPCs, designed to not stand out. Even designs like Zhongli that are meant to be simple frustrate me because they're overloaded with intricate patterns and details. I'm kinda salty, if you haven't noticed, that the exact reasons why I almost like Charlotte's design are the same ones that people use to relentlessly shit on her.

There are also some things that are clearly encouraged or avoided with Genshin's character designs, most of them from what I can tell for practical reasons. There are essentially no female characters with loose hair that reach any longer than their shoulders, and even if they do, they part at the middle because the "character needs to be visible from the back". Because the characters are expected to always be running and moving freely, most characters tend to have things in them that move and sway as they do - detached sleeves, scarves, just random shit stapled on them, Baizhu's unwearable abomination of a coat, etc.

miHoYo has created certain expectations and guidelines for their character design and I despise those. It's just the way that I am. If you like them, then great, I'm sure you like most of the characters. However, if you're like me and dislike them, then those things are never gonna go away. Characters are always going to be drowning in details, they're always going to have stuff dangling off of them, they're always going to have short or tied or braided hair, etc. Does it give Genshin an unique visual identity? Sure, but whether or not that's a good thing entirely depends on the person.

To me, I'm not going to see an improvement or a downgrade in any of the designs because all the conventions they adhere to that I dislike are still there, and when they're gone, people complain. It's just the standard that's been set.

But really what I dislike about the wording of your post is that it essentially implies that you've read mine as an objective observation of Genshin's designs. Like I'm the authority on the designs and that I know exactly how or how not to make good designs. Like:

A lack of “simplicity” isn’t really the issue, anyway.

But it is. For me. I don't like Zhongli's design. I don't care if other people do, I know that I don't like it and I know what I don't like. Whether or not it's Objectively Good Design doesn't matter to me. I'm sure it is, he's a very popular character, but that won't affect how I feel about him.